Apparatus and methods for power stealing by controllers

Abstract

A controller for use in a climate control system includes a power stealing circuit connectible with a control of the climate control system and configured for stealing power via a signal from a power source through the control. An overcurrent limiting circuit is configured to limit a first portion of the signal to prevent a false call for operation of the control. The overcurrent limiting circuit is further configured not to limit a second portion of the signal to prevent a false call, where the control is configured to recognize only the first portion as determinative of whether the signal is a call for operation.

What is claimed is: 
     
       1. A controller configured for use in a climate control system, the controller comprising:
 a power stealing circuit configured to be connectible with a control of the climate control system and configured for stealing power from a power source via a signal through the control, without using a common (C) wire from the power source and an RC/RH line where power is drawn when a relay switch in the controller is opened/closed; and 
 an overcurrent limiting circuit configured to limit a first portion of the signal to prevent a false call for operation of the control; 
 the overcurrent limiting circuit further configured not to limit a second portion of the signal to prevent a false call, where the control is configured to recognize only the first portion as determinative of whether the signal is a call for operation; 
 wherein the first portion is a positive portion of the signal and the second portion is a negative portion of the signal. 
 
     
     
       2. The controller of  claim 1 , wherein the controller comprises a thermostat. 
     
     
       3. The controller of  claim 1 , wherein the power stealing circuit is configured to steal power via the first and second portions of the signal when the signal is determined not to be a call for operation. 
     
     
       4. The controller of  claim 1 , wherein the power stealing circuit is configured to steal power via the second portion of the signal when the signal is determined to be a call for operation. 
     
     
       5. A controller configured for use in a climate control system, the controller comprising:
 a power stealing circuit configured to be connectible with a control of the climate control system and configured for stealing power from a power source via a signal through the control, without using a common (C) wire from the power source and an RC/RH line where power is drawn when a relay switch in the controller is opened/closed; 
 an overcurrent limiting circuit configured to limit a first portion of the signal to prevent a false call for operation of the control, the overcurrent limiting circuit further configured not to limit a second portion of the signal to prevent a false call, where the control is configured to recognize only the first portion as determinative of whether the signal is a call for operation; and 
 a call generator configured to provide a call for operation of the control, the call including a signal portion configured to be unrecognized by the control as determinative of whether the signal is a call for operation and to provide a voltage for driving power stealing by the power stealing circuit. 
 
     
     
       6. The controller of  claim 5 , wherein the first portion is a positive portion of the signal and the second portion is a negative portion of the signal. 
     
     
       7. The controller of  claim 5 , wherein the call is a call for activating one or more of the following: a furnace control, a universal control, and an air handler control. 
     
     
       8. A controller configured for use in a climate control system, the controller comprising:
 a power stealing circuit configured to be connectible with a control of the climate control system and configured for stealing power from a power source via a signal through the control, without using a common (C) wire from the power source and an RC/RH line where power is drawn when a relay switch in the controller is opened/closed; 
 an overcurrent limiting circuit configured to limit a first portion of the signal to prevent a false call for operation of the control, the overcurrent limiting circuit further configured not to limit a second portion of the signal to prevent a false call, where the control is configured to recognize only the first portion as determinative of whether the signal is a call for operation; and 
 a call generator configured to provide a call for operation of the control, the call including a signal portion configured to be unrecognized by the control as determinative of whether the signal is a call for operation and to provide a voltage for driving power stealing by the power stealing circuit; 
 wherein the power stealing circuit is configured to steal power via a call signal path. 
 
     
     
       9. A method performed by a controller in a climate control system, the method comprising:
 configuring and sending a signal having first and second portions to a control of the climate control system such that only the first portion is determinative of whether the signal is a call for operation of the control; 
 limiting the first portion to prevent a false call for operation of the control; and 
 stealing power during at least the second portion, without using a common (C) wire from power source and an RC/RH line where power is drawn when a relay switch in the controller is opened/closed; 
 wherein the first portion is a positive portion of the signal and the second portion is a negative portion of the signal. 
 
     
     
       10. The method of  claim 9 , wherein the controller comprises a thermostat. 
     
     
       11. The method of  claim 9 , wherein the control is one or more of the following: a furnace control, a universal control, and an air handler control. 
     
     
       12. The method of  claim 9 , further comprising:
 receiving a power signal from a power source of the climate control system; and 
 configuring the signal to the control with an amplitude different from an amplitude of the signal from the power source. 
 
     
     
       13. The method of  claim 9 , wherein power is stolen during both the positive and negative portions. 
     
     
       14. A method performed by a controller in a climate control system, the method comprising:
 configuring and sending a signal having first and second portions to a control of the climate control system such that only the first portion is determinative of whether the signal is a call for operation of the control; 
 limiting the first portion to prevent a false call for operation of the control; 
 stealing power during at least the second portion, without using a common (C) wire from power source and an RC/RH line where power is drawn when a relay switch in the controller is opened/closed; and 
 generating a call for operation of the control, the call including a signal portion configured to be unrecognized by the control as determinative of whether the signal is a call for operation and to provide a voltage for driving power stealing. 
 
     
     
       15. The method of  claim 14 , wherein the first portion is a positive portion of the signal and the second portion is a negative portion of the signal. 
     
     
       16. A controller configured for use in a climate control system, the controller comprising:
 a power stealing circuit configured to be connectible with a control of the climate control system and configured for stealing power via a signal from a power source through the control, without using a common (C) wire from power source and an RC/RH line where power is drawn when a relay switch in the controller is opened/closed; and 
 an overcurrent limiting circuit configured to limit only a positive portion of the signal to prevent a false call for operation of the control, where only the positive portion is determinative of whether the control recognizes the signal as a call for operation. 
 
     
     
       17. The controller of  claim 16 , further configured to use a voltage across a dropping resistor of the control to drive the power stealing circuit. 
     
     
       18. The controller of  claim 16 , wherein the controller comprises a thermostat. 
     
     
       19. The controller of  claim 16 , further comprising a call generator configured to provide a call for operation of the control, the call including a signal portion configured to be filtered out by the control. 
     
     
       20. The controller of  claim 19 , wherein the call generator comprises a switching device including one or more of the following: a relay, a triac, a thyristor, a transistor, a diode, a diode in series with a relay, a resistor in series with a relay, a voltage divider, and a MOSFET.